Selection and use of harmful gas detectors

For various types of production sites and testing requirements, selecting the right gas detector is a must for everyone involved in safety and hygiene.

1Select the reference factors for the gas detector Confirm the type and concentration range of the gas to be detected: The gas types encountered in each production department are different. When selecting a gas detector, all possible conditions must be taken into consideration. If methane and other less toxic alkanes are present, the choice of methane detection alarm is undoubtedly the most appropriate. This is not only because the methane detection alarm is simple to use and has a wide application, but it also has the characteristics of convenient maintenance and calibration. If there are toxic gases such as carbon monoxide, hydrogen sulfide, etc., we must first select a specific gas detector to ensure the safety of workers, such as carbon monoxide detector, hydrogen sulfide detection alarm. Composite gas detectors may achieve a multiplier effect, such as methane and oxygen two-parameter alarms.

Now more choices in the coal mining industry should belong to the portable gas detector, because the portable instrument is easy to operate, small size, can be carried to different production sites, electrochemical detector using alkaline batteries, can be used continuously for 1000 hours; new type of LEL Detectors, PIDs, and hybrid instruments use rechargeable batteries (some have used memoryless nickel-metal hydride or lithium-ion batteries), making them generally capable of continuous operation for nearly 12 hours, so as such instruments in various types of factories and the health sector The use of more and more.

If it is in an open place, such as an open work shop using such an instrument as a safety alarm, a gas detector worn on the body can be used because it can display the concentration of toxic and harmful gases on site continuously, in real time and accurately. Some of these new instruments are also equipped with vibration alarm attachments to avoid audible alarms in noisy environments and computer chips to record peaks, STELs (short-term exposure levels for 15 minutes) and TWA (8-hour statistical weights) Average) - Provides specific guidance for worker health and safety.

If entering a confined space, such as a reaction tank, storage tank or container, sewer or other underground pipelines, underground facilities, closed agricultural granaries, railroad tankers, shipping cargo tanks, tunnels, etc., the personnel must be inspected before entering. , but also to test outside the confined space. At this point, the multigas detector must be selected. Because the gas distribution and gas types in different parts of the confined space (upper, middle, and lower) are quite different. For example, the proportion of combustible gas in the general sense is lighter. Most of them are distributed in the upper part of the confined space; the proportion of carbon monoxide and air is almost the same and is generally distributed in the middle of the confined space; while the heavier gas such as hydrogen sulfide exists in the confined The lower part of the space. At the same time, oxygen concentration is also one of the types that must be tested. In addition, a detector that can detect organic gases is also needed if the possible volatilization and leakage of organic substances in the tank are taken into consideration. Therefore, a complete closed-space gas detector should have a built-in pumping function - so that it can be detected in non-contact, sub-area; multi-gas detection - to detect different space distribution of hazardous gases, including inorganic gases and organic gases With oxygen detection function - to prevent lack of oxygen or oxygen-rich; small size, does not affect the work of the portable instrument. Only in this way can the absolute safety of workers entering the confined space be guaranteed.

2 Problems to be noted when using the gas detector 2.1 Attention to regular calibration and detection The toxic and harmful gas detectors are also measured in a comparative way as other analysis and testing instruments. First, use a zero gas and one The standard concentration of gas calibrates the instrument, and the calibration curve is stored in the instrument. When measuring, the instrument compares the electrical signal generated by the gas concentration to be measured with the standard concentration of the electrical signal to calculate the accurate gas concentration value. Therefore, zero calibration of the instrument at any time, and regular calibration of the instrument is an indispensable task to ensure accurate measurement of the instrument. It should be noted that at present, many gas detectors can replace the detection sensors. However, this does not mean that one detector can be equipped with different detector probes at any time. Whenever a probe is replaced, the instrument must be recalibrated in addition to a certain sensor activation time. In addition, it is recommended to respond to the standard gas of the instrument before using it to ensure that the instrument really protects the instrument.

2.2 Note Detection Interference Among Various Sensors In general, each sensor corresponds to a specific detection gas, but any kind of gas detector may not be absolutely effective. Therefore, when selecting a gas sensor, it is necessary to know as much as possible the interference of other gases to the sensor, so as to ensure accurate detection of the specific gas.

2.3 Pay attention to the life of various sensors All types of gas sensors have a certain useful life, that is, life. Generally speaking, in portable instruments, LEL sensors have a long life, generally about three years; photoionization detectors have a life expectancy of four years or more; electrochemical specific gas sensors have a relatively short life span, and generally In one year to two years, the oxygen sensor has the shortest life span of about one year. The life of the electrochemical sensor depends on the dryness of the electrolyte, so if it is not used for a long time, sealing it in a lower temperature environment can prolong the service life. Because of the relatively large size of the stationary instrument, the life of the sensor is longer. Therefore, it is necessary to detect the sensor at any time and use it within the effective period of the sensor as soon as possible. If it fails, replace it in time.

2.4 Concentration measurement range of the detection instrument Various types of toxic and harmful gas detectors have a fixed detection range. Only when the measurement is completed within its measurement range can the instrument be accurately measured. However, measuring over a long period of time may cause permanent damage to the sensor.

In short, toxic and harmful gas detectors are powerful tools for ensuring industrial safety and staff health. We must choose the right gas detector according to the specific environment and the required function. At present, the detectors available for our selection include various combinations of fixed/portable, single gas/multi gas, inorganic gas/organic gas, and the like. Only by choosing the right gas detection equipment can we really do more with less and take preventive measures.